My solution for "guns for battle" keeps getting marked as wrong and I don't know why. Any ideas?

import java.util.*;
import java.io.*;

public class Gunner{
public static void main(String[] args) throws Exception{

         StreamTokenizer in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
        PrintWriter out = new PrintWriter(System.out);

        in.nextToken();
        int n = (int)in.nval;
        int x = (2 * n) + 1;

        int r = 1, c=1;
        while( r <= x)
        {
            while(c <= x){
            if(r == c) out.print(0+" ");
            else out.print((r-1) + (c-1))+" ");

            out.flush();
            ++c;
            }
            out.println();
            out.flush();
            c = 1;
            ++r;
        }
}
}